FIGS. 1 through 4 show a prior art tangential cutting insert 500. The cutting insert 500 has two identical end surfaces 502a, 502b. Each end surface 502a, 502b is provided with an abutment surface 504. A peripheral side surface 510 extends between the two opposing end surfaces 502a, 502b. The peripheral side surface 510 is comprised of two opposing major side surfaces 512a, 512b, two opposing minor side surfaces 514a, 514b, and corner side surfaces 516a, 516b, 516c, 516d that are located between adjacent major side surfaces 512a, 512b and minor side surfaces 514a, 514b. A peripheral edge 520a, 520b is formed at the intersection of each end surface 502a, 502b and the peripheral side surface 510. The cutting insert 500 also includes a through bore 590 that passes between the opposing major side surfaces 512a, 512b. 
In a major side view of the cutting insert (see FIG. 3), each end surface 502a, 502b has four corners 530a, 530b, 530c, 530d including two diagonally opposed lowered corners 530a, 530d and two diagonally opposed raised corners 530b, 530c. 
The peripheral edges 520a, 520b include two sets of cutting edges. As seen in FIG. 1, each set includes a raised corner cutting edge 540b associated with a first corner side surface 516b, a major cutting edge 542b adjacent to the raised corner cutting edge 540b and extending along a first major side surface 512b, and a raised corner wiper edge 544b adjacent to the raised corner cutting edge 540b. The raised corner wiper edge 544b extends along a first minor side surface 514b which shares the first corner side surface 516b with the first major side surface 512b. 
Milling cutters having such prior art cutting inserts 500 retained therein, cut in either a perpendicular direction or a horizontal direction with center cutting. When trying to ramp cut using a milling cutter with such prior art cutting inserts, a dull edge of the cutting insert 500 scrapes against the workpiece because the cutting insert 500 has no clearance. Thus, the workpiece to be cut is deformed and potentially hardened, and the life of the cutting insert 500 is reduced.